This invention relates to a device for shifting a contact arrangement for a thermally operated protective relay from self-locking to automatic resetting. More particularly, the invention relates to such a device, having a contact arrangement consisting of a resiliently supported make contact, a break contact, and a double-throw contact, in which the make contact is shifted in the closing direction by means of a piston slide which can be locked and has means for cancelling the self-locking condition. The piston is freely movable and supported against a spring force.
One known device of the above-mentioned type is provided with a plunger which is supported for motion transverse to the travel direction of the resiliently supported make contact and which takes over the shifting and resetting function. In this device, the plunger is locked in the automatic resetting position by a separately provided eccentric. An additional return spring is required for restoring the plunger to the starting position.
In a known thermal overload relay, the shifting is accomplished by pushing the reset button in to the stop and pushing a separately provided slider into the range of motion of the reset button. When the reset button is released, the toggle switch is shifted to manual reset.